2 questions:
1 - would these be a good match (light and look) for 5000K Nokya fog lamps? I've read the stock Sylvania bulbs are 4300K, so 4100K shouldn't look much different.

2 - if you don't think these would be good for a plug-and-play replacement, what would you recommend?

At this point in time, HID is not an option (aside from the supposed legal point), neither is any kind of retrofit; and procuring projectors is out of the budget.

With the recommendation for the PIAA's, it sounds like I would get a significant improvement over OEM, without a significant expense; while not being nearly as good as the HID or other retrofit options.